Interferon-induced enzyme activities such as the oligo (2' yields 5') adenylate synthetase, the 67K dalton protein kinase and oligo (2' yields 5') A phosphordiesterase are investigated with a goal of understanding their role in the action of interferon, the induction of interferon by double-stranded RNA and, perhaps, control of cell growth and differentiation. An efficient high yield chemical synthesis of adenyl (2' yields 5') adenylyl (2' yields 5') adenosine (2',5'-oligo A core) has been completed to give material identical with that isolated from biological sources. High levels of oligo (2' yields 5') adenylate synthetase have been found in human lymphoblastoid cell lines such as Namalwa and 1788.